simple regex issue

eggbaconsandwich · Mar 5, 2015

Hi tek-tips.

Perl noob here, I have the following code for turning anything to lower case after 3 slashes :

Perl:

$input = 'tea/coffee/eggs/BACON'; 
$output = $input =~ s/^((?:.*?\/){3}(.*)$/$1.lc($2)/er;
print $output;

Question, how can I quickly reverse the application of lc and only apply it to $1 instead of $2? I.e. turn anything to lower case up until finding 3 slashes, once 3 slashes found do not alter the rest.

Thanks in advance.

prex1 · Mar 6, 2015

I would do this in a much faster way not using regexes:

Perl:

$input = 'Tea/Coffee/Eggs/Bacon'; 
@spl = split(/\//,$input,4);
map{$_=lc}@spl[0..2];
$output=join'/',@spl;
print $output;

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feherke · Mar 6, 2015

Hi

I generally agree with Franco, but in this case I would use a regular expression :

Perl:

[navy]$input[/navy] [teal]=[/teal] [i][green]'Tea/Coffee/Eggs/Bacon'[/green][/i][teal];[/teal]
[navy]$output[/navy] [teal]=[/teal] [navy]$input[/navy] [teal]=~[/teal] [b]s[/b][fuchsia]!^((?:[^/]*/){3})!\L$1![/fuchsia]r[teal];[/teal]
[b]print[/b] [navy]$output[/navy][teal];[/teal]

Feherke.
feherke.ga

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simple regex issue

eggbaconsandwich

Programmer

prex1

Programmer

feherke

Programmer

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